odd issue- top end bog

[honda400ex2003]

Hey guys,

more of just a common question but based on my 400ex- anyone have a top end bog no matter what you do to it?

not sure where to go with my 400, 3 issues left that are a possibility

jetting, CDI box, or a coil

My 400 will run great until 4th and 5th pinned for a while. it will run about 63 max which is quite slow for my 440. it sputters like it is hitting a limiter, just falls on its face.

list of mods on the 400-

11:1 440cc
200 main, 52 pilot, 3rd notch
450r carb
stage 2 hot cam
full exhaust
k&n intake

I have went from a 170 to a 200 main with the same results on jetting, leading me to think that it is something else. I checked the valves last night, they are good to go and in spec. Took the stator cover off to check for moisture in there, it looked ok as well.

It seems like the coil could be going or the CDI could be getting goofy but it has been doing it since last fall so i would have thought that either of those would have went out by now. im not sure if its the coil, i dont have my stocker any more. I thought i did but dont.

I thought that it was jetting related and still do... i have tried every jet that i have in my box, 170, 172, 175, 178, 180, 182, 185, 188, 190, 192, and drilled my own 200 and 210 to try them out. nothing makes it run any better, but they will make it worse. it ran really sluggish with the 210 so i went back to a 200 and have left it for a few days now.

It does need a 55 pilot on it but that wont effect the top end when it is wound out. it pulls so well up till it is pegged out on a long run that it just has me befuddled.

thought on what it could be? anyone have a CDI and a stock coil that they would either let me borrow or trade some other parts for? I have some extended hubs and stuff that are in my for sale thread that id trade for some new parts.

Thanks,
Steve

[beastlywarrior]

Sounds like cdi to me

[DragonGunner]

1. Clean your filter and re oil if you haven't in a while...its getting colder out so you might throw the lid on if its off to cut down on air. How far out is your air mixture screw...a half a turn more out can make the differance.

[honda400ex2003]

im leaning toward a CDI as well.

filter is cleaned, as well as the jetting being on the rich side. I have ran everything from a 6 hole lid to no filter at all trying things along with all of those jets.

it has been an on going issue for a year now, i just get irritated with it and leave it alone. it runs fine most of the time, just when i run wide open for longer periods of time.

keep the ideas coming guys!

steve

[CJM]

If you need a cdi let me know steve, Im pretty sure I have my old stock unit kicking around somewhere.

[mcmike]

Put a new plug in it. Take it out and let it do it's thing. Bring it back and check the color of the plug. If it's brown your good, probably your rev limit or CDI. If it's black your too rich.

[blacknblue#2]

Put a new plug in it. Take it out and let it do it's thing. Bring it back and check the color of the plug. If it's brown your good, probably your rev limit or CDI. If it's black your too rich.

I very well could be wrong on this so dont hold me to it, but i dont think you will get an accurate plug reading if you dont have accurate fire

[honda400ex2003]

im convinced that it is either the coil or the cdi. Thanks for hooking me up Marc! I have been messing with jetting for ever and just cant get a good reading on the plug and cant get it to run with a crap.

steve

[CJM]

See if you can make the inside of the coil tighter where it fits onto the threaded part of the plug. It fits but isnt very tight like I said. CDI was fine tho, shouldnt give you any issues.

[honda400ex2003]

Well... I added the coil and CSI with the same results. Back to jetting as the main cause for the poor running up top. It just runs so well everywhere else that I can't believe it could be jetting related.

Thanks again Marc, I still haven't written them off as issues that could be part of it. It did seem to rev higher than it previously has before stuttering.

Steve

[honda400ex2003]

Well after about an hour or so of messing around tonight. I finally got it all dialed in again. Went to a 58 pilot and went down to a 180 main. The top end sputter went away and the back fire on throttle let off is gone too. I could possibly go to a 178 but figured I'd leave it at a 180 and run it for a while.

Thanks again Marc!

Steve

[CJM]

Your welcome steve!

[honda400ex2003]

Hopefully it will be trouble free again for quite some time. :) I'm looking forward to riding more next summer now that its running better.

Steve

[honda400ex2003]

ran great again tonight :D mission finally complete after a long time coming. i finally got irritated and just left it for a long time. i can finally start enjoying riding again :D

steve